Differential flotation of ores



Patented gent, 25, E

new

tars

GUQTAIF BELT 3- n, or BUTTE, Montana.

FLOTATIO N F ORES.

Ho Drawing.

To all whom it may cont-em:

Be it known that I, GUs'rAr AXEL HnnLs'rRANn, a subject of the King of Sweden, residing at'Butte, in the county of Sil- 5 Ver Bow, State0f- Moiitana, have lnvented certain new and useful Improvements in Differential Flotation of ()res; and I do hereby declare the following to be a full, clear, and exact description of the invention,

1 such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the,concentration of ores b flotation, and more particularly to the ifierential flotation of mixed sulfide ores. The invention has for its object the pro ision of an improved method of con-' 'centratmgmixed 'or complex sulfide ores by differential flotation. More particularly, the invention aims to rovide 'animproved method of concentrating by diflerential flotation a mixed or complex sulfide ore containing zinc sulfide or blende associated with other metallic sulfides.

The complex or mixed sulfide ores, such, for example, as an ore carrying sulfides of lead, zinc, copper and iron, have offered many difliculties to treatment by gravity concentration as well as by flotation, and in the case of many ores of this type it has here tofore been practically impossible to make an economic separation'of the various metalliferous constituents of the ore from one another. Y 35. The present invention contemplatesan improved method of treating complex or mixed sulfide ores containing zinc sulfide associatcd with one or more other metallic sulfides, such as iron, lead and copper sulfides, where 40 by such other metallic sulfide or sulfides are differentially separated by flotation from the zinc sulfide. Such a complex or mixed sulfide ore may also carry precious metallic values, particularl silver as metallic silver 5 or as a simple sul de or as one of the many forms of' silver minerals. In accordance with the method of the invention, any such precious metallic values in the ore .pass. in

substantial amount along with the'aforementioned other metallic sulfides and are thus separated from the zinc sulfide in the ore. 1

The objectof differential flotation in the treatment of a complex or mixed sulfide ore of the'aforementioned character is the eco- .IlOlDlC advantage resulting from the segrega- Application filed June 2a 1922. Serial n' 570,231. a

tion of thevaluable minerals in the ore. is desirable in treating such a mixed sulfide ore by differential flotation to make:

(1) A lead product free from zinc,

(2) A zinc product free from lead, iron and copper (3) A segregation of copper and iron with the lead rather than with the zinc, partreated with sodiummonosulfide or withone of the polysulfides of sodium, or with any other alkali or alkali earth sulfide, and.

the thus treated me is subsequently subjected to a flotation operation in the course of which the sulfides of leadand/or iron and/or copper and/or silver and/0r gold are selectively or diflerentially removed from the ore pulp in the overflow froth, leaving behind in the'ore pulp the greater part of the zinc. sulfide present in the ore. In other words, the treatment of the ore pulp with the relatively small amount of an alkali or alkali-earth sulfide contemplated by the present invention substantially inhibits the flotation of zinc sulfide while permitting the flotation of the other metallic sulfides present in the ore. I 9

vI am well aware that sodium monosulfide and polysulfides are recognized flotation reagents and that their use has heretofore been suggested in the flotation of oxidized minerals (such as lead and copper carbonates) not otherwise amenable to flotation without the use of the sodium sulfide.

Sodium sulfide has also been used, I believe, i

in the flotation of various sulfide minerals refractory to such treat nent because of surface oxidation. The object of us ng SOdlllIIl monosulfide or sodium polysulfides in such cases is to obtain asulfidizing actio on the pxidized or partially oxidized mine als, thus permitting the applicationof flotation to the recovery of minerals which otherwise are not amenable to flotation treatment. I am also aware that it has heretofore been proposed to eflect diflerential flotation of mixed sulfide ores by submitting such ores to flotation separation in a circuit containing in solution from 0.1% to 1% of a sulfide of an alkali metal or earth, As contrasted with these prior suggestionsof the use in the flotation of ores of an alkali metal or earth sulfide, my present invention contemplates an improvement in the diflerential flotation of mixed sulfide ores involving the preliminary treatmentof the mixed sulfide ore with a relatively small amount of an alkali or alkali-earth sulfide, as for example, from about one to seven pounds of sodium sulfide per ton of ore at a pulp dilution of about four parts of water to one part of ore, by weight. v

The general procedure in carrying out the process of the invention is as follows: Commercial crude sodium sulfide equivalent to from about one to seven pounds of sodium sulfide per ton of ore is added to the mixed sulfide ore, preferably in the grinding mill, along with about one-tenth to one pound per ton of ore of suitable oil such as coal tar creosote, or other equivalent flotation reagent. The amount of sodium sulfide will vary with the nature of the ore and the pulp dilution at which the diflerential flotation is carried out. The ore is ground fine enough to free the minerals, and also fine enough for flotation.

The diflerential result can be obtained.

with an reasonable pulp density, for example, our parts of water to one part of ore, by weight, but for a given ore the amount of sodium sulfide per ton of ore will be relatively smaller with low pul dilution than with high pulp dilution. A constant pulp density is essential for the best difierential results after the reagents have been properly proportioned to a given pulp density. The ore pulp is now subjected to treatment in a flotation machine in order to separate the sulfides of lead, iron and copper from the zinc sulfide. Any type of flotation machine commonly used in the art may be employed for this purpose. small amount of additional oil, such as cresyllc acid or pine oil, may be added in the flotation machine. However, an excess of oil is to be avoided because any excess of oil tends to destroy the difl'erential results. The diflerential flotation is usually made in cold pulp.

The ore pulp remaining after the aforementioned differential flotation treatment contains the greater part of the zinc sulfide present in the original ore. This remaining ore pulp 1s now subjected to a further flotation operation for the removal therefrom of the zinc sulfide. This subsequent flotation for removing zinc sulfide from the ore neeepea pulp may be carried out under either alkae me or acid conditions. In alkaline flotation,

T have obtained good results with one to two pounds of oil mixtures (consisting of coal per sulfate, per ton of ore. lln acid flotation,

good results have been obtained with a fraction of a pound of pine oil, per ton of dre, and sulfuric acid suficient to make the pulp slightly acid. The ore pulp, with the additional reagents above mentioned, is now subjected to a second flotation operation and a froth concentrate is obtained containing substantially all of the zinc sulfide present in the ore. With acid pulp the flotation of the zinc sulfide is facilitated by heating the ore pulp to about 95 F. The zinc flotation under alkaline conditions is usually carried out in cold pulp.

A departure from the above procedure may be desirable in the treatment of certain ores. For example, the sodium sulfide may be introduced into the ore pulp at difi'erent stages during the process in addition to the amount added in the grinding mill, or the entire amount of this reagent may be added in the flotation machine, or to the ore pulp just prior-to its introduction into the flotation machine. Moreover, all of the oil may be added in the grinding mill, or all may be added in the flotation machine or to the ore pulp just prior to its introduction into the flotation machine.

The method of the invention has a wide field of application and has given excellent 7 spects the present invention, is merely in the relative soluble sulfide content, one pound of 60% commercial crude sodium sulfide being equivalent to 0.6 pound sodium sulfide.

. EXAMPLE No. 1-Onn A.

The ore was ground wet to along with four pounds 0' commercial crude sodium sulphide (62% sodium sulphide) and about 0.1 pound of ,an oil mixture (consisting of coal tar creosote and 10% pine oil per ton of ore.

ass 65 mesh,

The lead-iron concentrate was obtained by the addition of about 0.15 pound, per

ton of ore, of the oil mixture to an ore pulp rec of three parts of water to one partof ore, by weight, and subjecting the ore pulp to a flotation operation.

The remaining ore pulp was then slightly acidified with sulphuric acid and heated to 95 F. and subjected to a further flotation operation with additional amount of oil mixture to obtain the zinc-concentrate.

Aeeay.

Wt. per Per oz Per Per Per For Product. cent cent A cent cent cent cent -of Cu. insol. Fe. Zn. Pb. total.

Heed 100.0 0.18 0.7 .4 1.7 16.2 2.02

Pin-F0. conc 7.1 1.13 32. 8.6 19.6 13.1 22.30 Zn. colic 23.3 0.45 16.5 5.5 0.4 80.2 1.34 Zn.middling....... 6.7 5.1 0.6 14.3 0.70 Telling 62.9 0.3 0.25 0.0 0.12

Total 100.0

TABLE No. 1ARmcovna-Cnc. T0 100%.

Per cent of total. Product.

Ag. Fe. Zn. Pb.

Head 100.0 100.0 100.0 100.0

Pb.-Fe. c0110 .04. 7 s2. 0 t; 0 7a 4 Zn. conc 57. 4 5. 5 8 l5. 4 Zn. middling. 5. 1 2. 4 5. 0 2. 5 Taillnz 2.8 0.3 1.5 3.7 Total 100.0 100.0 100.0 100.0

The zinc concentrate in the foregoing example was obtained by acid flotation.

The following tabulation shows the leadiron and zinc concentrates combined in a single product in order to represent the results of a collective flotation process Assay.

Wt. per Per 07 Per Par Par Per Product. cent cent cent cent cent cent 0! Cu. insol. Fe. Zn. Pb. total. a

Pb,-Fc. and Zn. cone.

TABLE No. 2A-Racovnnr-Cntc. To 100%.

. Per cent of total.

Product. I

Ag. Fe. Zn. Pb.

Pb.-Fe. and Zn conc.combd WA 88.3 92.0 03.8 Zn. mid. 5. 1 2. 4 5.9 2. 5 'r I 2.0 0.3 1.5 3.7 TOtBln. 100.0 100.0 100.0 100.0

The advantages of the method of the in- Vention applie to this articular ore (A) may be summed up as f0 lows:

creosote, per ton of ore.

by adding (1) A segregation into an economic product of comparatively small amounts of lead, iron and copper sulfides in the ore;

(2) The elimination of these sulfides assuresa high grade zinc product;

(3). A' segregation of an appreciable ExnMrL n no. 2- 000 a The ore was along with seven unds' of commercial; crude sodium sulphide (62% sodium sulphide') and about 0.1- pound of coal tar Thelead-i'ron concentrate was obtained about 0.1 pound of pine oil, per ton of ore, to an ore .pulp of four parts of 'water to one part of ore, by weight, and

subjecting the ore pulp to ation. v v

The zinc concentrate was obtained by subjecting the remaining ore pulp to a further flotation operation with sodium carbonate, 0.75 sulphate, two pounds 0 (consisting of coal tar oil,

a flotation operpound ofv copper an oil mixture coal tar creosote product is higher two. pounds of.

ground wet to pass 65 mesh,

and pine oil), per ton of ore.

I -Aeaoy'.

Wt. P P P .pcr er or e: or Product. cent 2 cent cent cent cent of insol. Fe. Zn. Pb.

total.

I I Heed....'..........-...100.0 .0 05.3 0.3 14.7 1.04- rn-Fe. 001.10.. 10.0 07.1 10.0 00.0 0.0 12.40 Zn.conc..... 21.0 37.0 as 0.4 00.0 0.21 Zn.mld... 3.4 7.1 75.2 .00 11.5 0.05 Tellin 04.4 0.4 0.1 0.0 ,Tr.

Tmnn'No. 1B--Bacovna1z C4nc. 1 010070;

Percent 0mm." Product.

Ag. Fe. Zn. Pb.

04.0 4.2 05.4 2.0 00.2 4.4 0.0 2.7 0.2 1.0 3.0 Total 100.0 100.0 100.0 100.0

' In the following tabulation the lead-iron and zinc concentrates have been combined (ill) to present the products lective flotation process:

Army.

obtained by a colaeeaoea TABLE No. 1CRECOVEBY-CALC. TO 100%.

Per cent of total.

Product.

Ag. Fe.

r Product. f of OzJLgz.

Per cent Fe For t Head Ag. conc Zn cone...

Pb.-Fe. and Zn. concs Telling.

Total Undoubtedly some silver exists in associa- TABLE No. 2B-REcovEnY-CALc. TO 100%.

this ore (0); but the indications are that Per cent of total.

erals. I

Acid zinc flotation followed difierential Product.

flotation in the foregoing example.

Pb.-Fe. and Zn. concs combd. Zn. middling railing EKAMIPIZE No. 4-ORE D.

The preliminary treatment of the ore in Total 10 the grinding operation was the same as in example No. 2.

ditions in contrast to conditions essential to zinc recovery.

EXAMPLE No. if-Unn C.

The preliminary treatment of the ore in the grinding operation was the same as in example No. l.

The silver concentrate was obtained under the same condition as set forth for the lead-iron concentrate in example No. l.-

The zinc flotation was carried out as in example No. 1, except that was not retreated.

Home.

the concentrate der the same condition as set forth for the lead-iron concentrate in example N0. 2.

The zinc flotation was carried out as in example No; 2.

Tn the zinc flotation, in examples Nos. 1, 2 and 4, the first or rougher, concentrate obtained was subjected to another flotation treatment (or cleaning operation) and the tailing from this cleaning operation is shown as zinc middling.

Assay.

Per cent I Pet Product.

Head.

Cu. cone tion with the principal "sulfide minerals in.

silver occurs largely as distinct silver min- The copper concentrate was obtained un- TAnLm N0. 1DRECOVmBY-CALC. TO 100%.

Per cent of total.

Product.

Ag. Fe. Zn.

Per cent Product.

I cent of cu JPert can lnsol.

Head...

53$ &

pet a EXAMPLE No. fan-Urn i E.

The ore was ground wet to pass mesh.

The lead concentrate was obtained with the addition oil three pounds of coercial naeaoaa crude sodium sulphide (02% sodium sulphide) and about one pound of an. oil mixture (consisting of 90% coal tar creoto one part of ore, by weight, and subjectmg. the ore pulp to a flotation operation.

Per Per For For Product. gi cent cent cent cent lnsol. Fe. Zn. Pb. total. I

Head 100. 71. 1. 3 2. 1 5. l

Pb. cone 9.1 14.5 2.0 7.9 58.6 g... 00.0 1.2 1.5 0.1

Total 100. 0

mm No. 1ERacovnnranc. To 100%.

- Per cent 01 total.

Product. 7

Fe. Zn. Pb.

Head 100. 0 100. 0 100. 0

' 14.3 34.0 08.3 & 7 65. 4 1. 7

w The foregoing exam le shows a good recovery of lead in a hig grade product.

EXAMPLE No. 0-0111; F.

I The ore was ground wet to pass mesh,

along with six pounds of C. P. sodium sulphide and about 0.15 pound of coal tar creosote,'per ton of ore.

The lead-iron concentrate was obtained by the addition of about 0.2 pound of an. oil mixture (consisting of 25% pine oil and 75% cres lic acid) per ton of ore, to an ore pulp of out parts of water to one part of ore, b weight, and subjecting the ore pulp to a otation operation.

The zinc concentrate was obtained by subjecting the remaining ore pulpto a further flotation operation, with the addition of one pound of sodium carbonate, 0.75 pound pound of an oil mixture (consisting of 90% coal tar creosote and 10% pine oil), per ton of ore.

Assay.

copper sulphate and about onezinc product. p

Theltreatment of a mixed sulfide ore with TABLE Nb. lF-Rmcovrmr-Canc. 1'0 100%.

' Per cent of total.

Product.

Total The quantity of oil that may be used in carrying out the method of the invention with good difi'erential results may be more or less than the amounts hereinbefore specified. Moreover, the method of the invention is not restricted to the use of sodium sulfide, but, on the contrary the difi'erential results contemplated by the invention may be secured by other soluble sulfides and in particular by'the polysulfides of sodium as well as by the sulfides of the other alkali metals and alkali-earth metals.

Chemically 1fpure reagents are not essential for the satis acto operation of the improved process of difierential flotation contemplated by the invention. Thus, the invention may be successfully practiced with commercial crude sodium sulfide (also commercial crude sulfides of the other alkali and alkali-earth metals) containing impurities such assulfites, hypo-sulfites, sulfates,

carbonates, and other salts.

The essential feature in the improved soluble sulfide) as a difl'er'ential flotation reagent when employed in accordance with the present invention is exhibited (1) in the acceleration of the flotation of lead and/or iron and/or copper sulfides, (2) in the inhibition of the flotation of zinc sulfide, and (3) inthe concentration of silver minerals in the difierential product rather than in the the relatively small amount of an alkali or alkali-earth sulfide contemplated by the present invention secures certain advantageous results among which may be mentioned the production of a relatively stable and easily removed froth, which is an important factor from the stand oint of practical mill operation. are t 0 method 01 the invention is appli to the difl'erential separation-of lead sulfide from zinc sulfide,"

the relatively small amount of alkali or alkali-earth sulfide employed insures satisfactory zinc flotation, especially if it is de-. sired to carry on acid zinc flotation, whereas the use of much larger amounts of the alkali or alkali-earth sulfide will unfavorably afl'ect the zinc flotation due to the presence in the ore pulp of an appreciable quantity of hydrogen sulfide gas and other products formed by the action of sulfuric acid on the alkali or alkali-earth sulfide.

From the foregoing description and examples, it will be evident to those skilled in the art that the method of the invention (3) The separation of cop er sulfide (particularly chalcopyrite an bornite) from zinc sulfide, and

(4:) The separation of lead and copper sulfides (partlcularly chalcopyrite and bornite) from zinc sulfide.

ll claim:

1. A process of concentrating by flotation an ore containing zinc sulfide and one or more other metallic sulfides, which comprises subjecting the ore to treatment with a soluble sulfide in amount, not exceeding about seven pounds per ton ofore, proportioned to eflectively inhibit the flotation of zinc sulfide, and subjecting the so treated ore to a flotation operation in whichthe flotation oil the zinc sulfide is in large part iibited.

2., A process of concentrating by flotation an ore containing zinc sulfide and one or more other metallic sulfides, which comprises subjecting the ore to treatment with a soluble sulfide in amount, not exceeding about seven pounds per ton of ore, proportioned to eflectively inhibit the flotation of zinc sulfide, subjecting the so treated ore to a flotation operation and thereby obtaining a concentrate containing a. relatively high percentage of such other metallic sulfide or sulfides, and thereafter subjecting the re maining ore pulp to another flotation operation under appropriate conditions permitting the flotation of the zinc sulfide.

3. A process of concentratin. by flotation an ore containing zinc sulfi e associated with one or more other metallic sulfides and with minerals of the precious metals, which comprises treating the ore with a soluble sulfide in an amount, not exceeding about seven pounds er ton of ore, proportioned to effectively Inhibit the flotation of zinc sulfide, and subjecting the thus treated ore to a flotation operation and thereby obtaining a froth concentrate containing a relatively high percentage of'the precious met als and said other metallic sulfide or sulfides while the flotation of the zinc sulfide is substantially inhibited.

4. A process of concentrating b flotation an ore containing lead sulfide an zinc sulfide, which comprises treating the ore with a soluble sulfide in amount, not exceeding about seven pounds er ton of ore, proportioned to efl'ectively inhibit the fiotation of the zinc sulfide, and subjecting the thus treated ore to a flotation operation and thereby obtaining a froth concentrate containing a relatively high percentage of the 1 lead sulfide and inhibiting in large part the flotation of the zinc sulfide.

5. A process of concentrating by flotation an ore containing lead, copper, and zinc sulfides, which comprises treating the ore with a soluble sulfide'in amount, not exceed- 'ing about seven pounds er ton of ore, proportioned to eflectively inhibit the flotation of zinc sulfide, and subjecting the thus treated ore to a flotation operation and thereby obtaining a icroth' concentrate containing a relatively high percentage of the lead and copper sulfides and inhibitin in large part the flotation of the zinc sulfie.

6. A process of concentrating by flotation an ore containing lead, iron, copper, and zinc sulfides, which comprises treating the ore with a soluble sulfide in amount, not exceeding about seven pounds per ton of ore, proportionedto eflectively inhibitthe flotation of zinc sulfide, and subjecting the thus treated ore to a flotation operation and thereby obtaininga froth concentrate containing a relatively high percentage ot the lead, iron, and copper sulfides and inhibitin in large part the flotation of the zinc su fide.

7. A process of concentrating by flotation an ore containing iron and zinc sulfides, which comprises treating the ore with a soluble sulfide in amount, not exceeding about seven pounds per ton of ore, pro ortioned to eflectivel inhibit the flotation o zinc sulfide, and so jecting the thus treated ore to a flotation operation and thereby obtaining a froth concentrate containing a relatively high percentage of the iron sulfide and inhibitin in large part the flotation of the zinc sulfie.

too

lllli 8. A process of concentrating by flotation reeopee a about seven pounds per ton of ore proper tide and inhibiting in large part the flotationed to effectively inhibit the flotation of tion of the zinc sulfide.

zinc sulfide, and subjecting the thus treate i In testimony whereof I efiix my "sigore to a flotation operation and thereby obneture. taining 25 froth concentrate containing e relatively high percentage of the copper sul- GUSTAF AXEL HELLSTRAND. 

